Process and apparatus for producing a golf ball with deep dimples

ABSTRACT

An apparatus and related techniques for making a golf ball with deep dimples are disclosed. The golf ball comprises a core and a cover layer, wherein the cover layer provides deep dimples that extend through the cover layer and/or into a layer or component underneath are disclosed. At least one percent (1%), preferably about five percent (5%), of the dimples of the ball comprise deep dimples. The cover may be a single layer or include multiple layers. If the cover is a multi-layer cover, the dimples extend to or into at least the first inner cover layer, and may extend to or into two or more inner cover layers. If the cover is a single layer, the dimples extend to or into the core. The dimples may be spherical or non-spherical, and the portion of the dimple that extends to or into the next inner layer may be the same or different shape as the outer portion of the dimple.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority upon U.S. ProvisionalApplication Ser. No. 60/337,123, filed Dec. 4, 2001; U.S. ProvisionalApplication Ser. No. 60/356,400, filed Feb. 11, 2002; and U.S.Provisional Application Ser. No. 60/422,247, filed Oct. 30, 2002.

FIELD OF THE INVENTION

The present invention pertains to the art of making golf balls, and,more particularly, to golf balls having deep dimples. The presentinvention also relates to processes and apparatuses for formingmulti-layer golf balls, and more particularly to processes and equipmentfor forming multi-layer golf balls having several deep dimples thatextend through the outer cover layer to and/or into one or more layersor components thereunder.

BACKGROUND OF THE INVENTION

Golf balls are typically made by molding a core of elastomeric orpolymeric material into a spheroid shape. A cover is then molded aroundthe core. Sometimes, before the cover is molded about the core, anintermediate layer is molded about the core and the cover is then moldedaround the intermediate layer. The molding processes used for the coverand the intermediate layer are similar and usually involve eithercompression molding or injection molding.

In compression molding, the golf ball core is inserted into a centralarea of a two piece die and pre-sized sections of cover material areplaced in each half of the die, which then clamps shut. The applicationof heat and pressure molds the cover material about the core.

Blends of polymeric materials have been used for modern golf ball coversbecause certain grades and combinations have offered certain levels ofhardness to resist damage when the ball is hit with a club andelasticity to allow responsiveness to the hit. Some of these materialsfacilitate processing by compression molding, yet disadvantages havearisen. These disadvantages include the presence of seams in the cover,which occur where the pre-sized sections of cover material were joined,and long process cycle times which are required to heat the covermaterial and complete the molding process.

Injection molding of golf ball covers arose as a processing technique toovercome some of the disadvantages of compression molding. The processinvolves inserting a golf ball core into a die, closing the die andforcing a heated, viscous polymeric material into the die. The materialis then cooled and the golf ball is removed from the die. Injectionmolding is well-suited for thermoplastic materials, but has limitedapplication to some thermosetting polymers. However, certain types ofthese thermosetting polymers often exhibit the hardness and elasticitydesired for a golf ball cover. Some of the most promising thermosettingmaterials are reactive, requiring two or more components to be mixed andrapidly transferred into a die before a polymerization reaction iscomplete. As a result, traditional injection molding techniques do notprovide proper processing when applied to these materials.

Reaction injection molding is a processing technique used specificallyfor certain reactive thermosetting plastics. As mentioned above, by“reactive” it is meant that the polymer is formed from two or morecomponents which react. Generally, the components, prior to reacting,exhibit relatively low viscosities. The low viscosities of thecomponents allow the use of lower temperatures and pressures than thoseutilized in traditional injection molding. In reaction injectionmolding, the two or more components are combined and reacted to producethe final polymerized material. Mixing of these separate components iscritical, a distinct difference from traditional injection molding.

The process of reaction injection molding a golf ball cover involvesplacing a golf ball core into a die, closing the die, injecting thereactive components into a mixing chamber where they combine, andtransferring the combined material into the die. The mixing begins thepolymerization reaction which is typically completed upon cooling of thecover material.

The present invention provides a new mold or die configuration and a newmethod of processing for reaction injection molding a golf ball cover orinner layer which promotes increased mixing of constituent materials,resulting in enhanced properties and the ability to explore the use ofmaterials new to the golf ball art.

For certain applications it is desirable to produce a golf ball having avery thin cover layer. However, due to equipment limitations, it isoften very difficult to mold a thin cover. Accordingly, it would bebeneficial to provide an apparatus and technique for producing arelatively thin cover layer.

Moreover, retractable pins have been utilized to hold, or center, thecore or core and mantle and/or cover layer(s) in place within aninjection mold while molding an outer cover layer thereon. In suchprocesses, the core or mantled ball is supported in the mold usingretractable pins extending from the inner surface of the mold to theouter surface of the core or mantled ball. The pins in essence supportthe core or mantled ball while the cover layer is injected into themold. Subsequently, the pins are retracted as the cover material fillsthe void between the core or mantle and the inner surface of the mold.

However, notwithstanding, the benefits produced through the use of theretractable pins, the pins sometimes produce centering difficulties andcosmetic problems (i.e. pin flash, pin marks, etc.) during retraction,which in turn require additional handling to produce a golf ballsuitable for use and sale. Additionally, the lower the viscosity of themantle and/or cover materials, the greater the tendency for theretractable pins to stick due to material accumulation, making itnecessary to shut down and clean the molds routinely. Accordingly, itwould be desirable to provide an apparatus and method for forming acover layer on a golf ball without the use of retractable pins.

SUMMARY OF THE INVENTION

The present invention provides, in a first aspect, a golf ball having aplurality of deep dimples defined along an outer surface of the golfball. The golf ball comprises a core and a cover layer disposed aboutthe core. The cover layer has an outer surface and a thickness anddefines a collection of dimples along its outer surface. At least 1%,and more preferably at least 5%, of the dimples have a depth greaterthan the thickness of the cover layer, and thus extend through the coverlayer.

In another aspect, the present invention provides a golf ball comprisinga core and a cover layer disposed about the core. The cover layer has athickness and defines at least two populations of dimples along an outersurface of the cover layer. A first population of dimples includesdimples having a depth greater than the thickness of the cover layer.The second population of dimples includes dimples having a depth lessthan the thickness of the cover layer. The first population of dimplesconstitutes at least a minority proportion of the total number ofdimples defined along the outer surface of the cover layer.

In yet another aspect, the present invention provides a moldingapparatus for forming a golf ball having a cover with a thickness and aplurality of dimples along its outer surface. The molding apparatuscomprises a first molding component that defines a hemispherical firstmold surface. The first mold surface has at least two populations ofoutwardly extending projections that form dimples. The populationsdiffer from each other by the height of the projections. The moldingapparatus also comprises a second molding component that defines ahemispherical second mold surface. The second mold surface has at leasttwo populations of outwardly extending projections that form the noteddimples. The populations differ from each other by the height of theprojections. The second molding component is adapted such that, uponengagement with the first molding component, a generally sphericalmolding chamber results from the first mold surface and the second moldsurface. The molding apparatus also comprises provisions for receivingone or more flowable materials used for forming the golf ball andadministering such materials into the molding chamber. At least onepopulation of the outwardly extending projections of the first moldsurface and at least one population of outwardly extending projectionsof the second mold surface have a projection height in the range of fromabout 0.005 inches to about 0.050 inches.

In a further aspect, the present invention provides a reaction injectionmolding apparatus for forming a golf ball core or intermediate ballassembly and an outer cover layer disposed about the core or ballassembly. The molding apparatus comprises a first mold defining ahemispherical first mold surface. The molding apparatus also comprises asecond mold defining a hemispherical second mold surface. The first andsecond mold surfaces have a first population of raised regions that formdimples along the cover layer of the golf ball. The first and secondmold surfaces also have a second population of raised regions eachhaving a height greater than the thickness of the cover layer of theball. The molding apparatus also comprises provisions for receiving twoor more flowable reactants utilized for forming the outer cover layer.The second population of raised regions constitutes a minorityproportion of the total number of dimples along the cover layer.

In yet another aspect, the present invention provides a process forproducing a golf ball having a particular proportion of deep dimplesalong an outer surface of the ball. The process comprises providing amolding apparatus that defines a generally spherical molding chamberresulting from a molding surface having a first population of raisedregions that form dimples in the golf ball, and a second population ofraised regions that form deep dimples in the golf ball. The process alsocomprises a step of providing a flowable molding material to the moldingapparatus. The process includes another step of positioning a core orintermediate ball assembly in the molding chamber. The process includesa further step of introducing the flowable molding material into themolding chamber between the core or intermediate ball assembly and themolding surface. The process comprises another step of hardening theflowable material to thereby form the golf ball. The second populationof the raised regions constitutes at least 5% of the total number ofdimples along the outer surface of the ball.

A further aspect of the invention is to provide equipment and methodsfor forming a golf ball having a dimpled cover that is thinner thantraditional cover layers.

Another aspect of the invention is to provide equipment and methods forforming a golf ball having a plurality of dimples in an outer coverlayer that extend to, and/or into, at least the next inner layer of theball.

Still further advantages of the present invention will become apparentto those of ordinary skill in the art upon reading and understanding thefollowing detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are not necessarily to scale, but are merelyillustrative of the present invention. Specifically, the figures are forpurposes of illustrating various aspects and preferred embodiments ofthe present invention and are not to be construed as limiting theinvention described herein.

FIG. 1 is a perspective view revealing the components of a preferredembodiment golf ball in accordance with the present invention.

FIG. 2 is a perspective view of a preferred embodiment molding assemblyin accordance with the present invention.

FIG. 3 is a planar view of a portion of the preferred embodiment moldingassembly taken in the direction of line 3—3 in FIG. 2.

FIG. 4 is a planar view of a portion of the preferred embodiment moldingassembly taken in the direction of line 4—4 in FIG. 2.

FIG. 5 is a detailed perspective view of a portion of the preferredembodiment molding assembly taken in the direction of line 5—5 in FIG.2. This view illustrates a mix-promoting peanut after-mixer inaccordance with the present invention.

FIG. 6 is a detailed view of the peanut after-mixer of the preferredembodiment molding assembly in accordance with the present invention.

FIG. 7 is a planar view of a portion of an alternative embodiment of themolding assembly in accordance with the present invention.

FIG. 8 is a planar view of a portion of an alternative embodiment of themolding assembly in accordance with the present invention.

FIG. 9 is a planar view of a portion of an alternative embodiment of themolding assembly in accordance with the present invention.

FIG. 10 is a flow chart illustrating a preferred embodiment process inaccordance with the present invention.

FIG. 11 is a cross-sectional view of another preferred embodiment golfball according to the present invention having a core and a single coverlayer having dimples, wherein one or more of the dimples extends throughthe cover to and/or into the underlying core.

FIG. 12 is a diametrical cross-sectional view of the preferredembodiment golf ball illustrated in FIG. 11.

FIG. 13 is a cross-sectional view of another preferred embodiment golfball according to the present invention having a core component and acover component, wherein the cover component includes an inner coverlayer and an outer cover layer having dimples formed therein, andwherein one or more of the dimples of the outer cover layer extends toand/or into the underlying inner cover layer.

FIG. 14 is a diametrical cross-sectional view of the preferredembodiment golf ball illustrated in FIG. 13.

FIG. 15 is a cross-sectional detail view of a portion of anotherpreferred embodiment golf ball according to the present invention havinga core and a cover illustrating a dual radius dimple that extendsthrough the cover into the underlying core.

FIG. 16 is a cross-sectional detail view of a portion of anotherpreferred embodiment golf ball according to the present invention havinga core and a cover illustrating a dual radius dimple that extendsthrough the outer cover layer to the outer surface of the core.

FIG. 17 is a cross-sectional detail view of a portion of anotherpreferred embodiment golf ball according to the present invention havinga core, an inner cover layer, and an outer cover layer, wherein theouter cover layer has a dual radius dimple that extends into the innercover layer.

FIG. 18 is a cross-sectional detail view of a portion of anotherpreferred embodiment golf ball according to the present invention havinga core, an inner cover layer, and an outer cover layer illustrating adual radius dimple that extends through the outer cover layer to theinner cover layer of the ball.

FIG. 19 is a schematic view of a preferred embodiment molding assemblyand a golf ball core according to the present invention.

FIG. 20 is a process flow diagram which schematically depicts a reactioninjection molding process according to the invention.

FIG. 21 schematically shows a preferred embodiment molding assembly forreaction injection molding a golf ball cover according to the invention.

FIG. 22 is a schematic process flow diagram illustrating a heat exchangecircuit utilized for an isocyanate feed source.

FIG. 23 is a schematic process flow diagram illustrating a heat exchangecircuit utilized for a polyol feed source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to equipment and methods for producingimproved golf balls, particularly a golf ball comprising a coverdisposed about a core in which the cover has one or more, preferably aplurality of, deep dimples or apertures that extend through the outercover to and/or into one or more layers underneath.

The present invention also relates to equipment and methods forproducing golf ball assemblies, i.e. cores having one or more mantle orinner cover layers disposed thereon, in which the core or ball assemblyincludes a plurality of deep dimples. The golf balls of the presentinvention, which can be of a standard or enlarged size, have a uniquecombination of cover thickness and dimple configuration. The presentinvention also relates to forming these golf balls, or at least certaincomponents thereof, by reaction injection molding techniques. Such deepdimples extend through at least one cover layer to, and/or into, theunderlying surface or component or layer.

With regard to dimple configuration or cross-sectional geometry, thepresent invention is based upon the identification of variousparticularly preferred characteristics as follows. Typically, forcircular dimples, dimple diameter is used in characterizing dimple sizerather than dimple circumference. The diameter of typical dimples mayrange from about 0.050 inches to about 0.250 inches. A preferreddiameter of a typical dimple is about 0.150 inches. The deep dimples mayhave these same dimensions or may have dimensions as described ingreater detail herein. As will be appreciated, circumference of a dimplecan be calculated by multiplying the diameter times p.

The depth of typical dimples previously utilized in the trade may rangefrom about 0.002 inches to about 0.020 inches or as much as 0.050inches. Preferably, a depth of about 0.010 inches is preferred fortypical or conventional dimples. It is preferred that the depth of adeep dimple as described herein is greater than the depth of a typicaldimple. Most preferably, the deep dimples have a depth that is deeperthan the depth of the typical dimples by at least 0.002 inches.

Specifically, depth of a dimple may be defined in at least two fashions.A first approach is to extend a chord from one side of a dimple toanother side and then measure the maximum distance from that chord tothe bottom of the dimple. This is referred to herein as a “chordaldepth.” Alternatively, another approach is to extend an imaginary linecorresponding to the curvature of the outer surface of the ball over thedimple whose depth is to be measured. This is referred to herein as a“periphery depth.” The latter format of dimple depth determination isused herein unless noted otherwise.

As described herein, the deep dimples included in the present inventionare particularly useful when molding certain layers or components aboutcores or intermediate ball assemblies. The depth of a deep dimple asdescribed herein may range from about 0.002 inches to about 0.140inches, more preferably from about 0.002 inches to about 0.050 inches,and more preferably from about 0.005 inches to about 0.040 inches.Preferably, a total depth of about 0.025 inches is desired. It is mostpreferred that the depth of a deep dimple as described herein is greaterthan the depth of a typical dimple and extend to at least the outermostregion of the mantle or core. Alternatively, the deep dimples preferablyextend to the bottom of a matched set of dimples on the mantle or thecore. The diameter of the deep dimples may be dissimilar, but preferablyis the same as other dimples on a ball, and may range from about 0.025inches to about 0.250 inches and more preferably from about 0.050 inchesto about 0.200 inches. A preferred diameter is about 0.150 inches.Generally, depth is measured from the outer surface of a finished ball,unless stated otherwise.

In one embodiment, the present invention relates to an apparatus andtechnique for forming a golf ball comprising a core and a cover layer,wherein the cover layer provides dimples including one or more deepdimples that extend to or into the next inner layer or component. Thecover may be a single layer or comprise multiple layers, such as two,three, four, five or more layers and the like. If the cover is amulti-layer cover, the dimples extend into at least the first innercover layer, and may extend into a further inner cover layer, a mantleor intermediate layer, and/or the core. If the cover is a single layer,the deep dimples may extend into a mantle layer and/or the core. Thecover layer(s) may be formed from any material suitable for use as acover, including, but not limited to, ionomers, non-ionomers and blendsof ionomers and non-ionomers.

In another embodiment, the present invention relates to an apparatus andtechnique for forming a golf ball comprising a core and a cover layer,wherein the cover layer provides dimples that extend to the core. Thegolf ball may optionally comprise a thin barrier coating between thecore and the cover that limits the transition of moisture to the core.The barrier coating is preferably at least about 0.0001 inches thick.Preferably, the barrier layer is at least 0.003 inches thick. In atwo-piece golf ball, a barrier coating is preferably provided betweenthe core and the cover.

In a further embodiment, the present invention relates to equipment andprocesses for forming a golf ball having a plurality of dimples alongits outer surface. In accordance with the present invention, one or moreof these dimples are deep dimples that extend entirely through the coverlayer of the ball, and to or into one or more underlying components orlayers of the ball. For instance, for a golf ball comprising a core anda cover layer disposed about the core, the deep dimples preferablyextend through the cover layer and to or into the core. If one or morelayers such as an intermediate mantle layer are provided between thecore and the cover layer, the deep dimples preferably extend through thecover layer and to or into one or more of those layers. The deep dimplesmay additionally extend into the core.

The deep dimples of the present invention may be spherical ornonspherical. Additionally, the portion of the deep dimple that extendsto, or into the next inner layer or component may be the same ordifferent size and/or shape as the outer portion of the dimple.

Turning now to the drawings, with reference to FIG. 1, a preferredembodiment golf ball 10 in accordance with the present invention isillustrated. The golf ball 10 includes a central core 12 which may besolid or liquid as known in the art. A cover 14 is surroundinglydisposed about the central core 12. An intermediate layer 16 may bepresent between the central core 12 and the cover 14. The presentinvention primarily relates to the cover 14 and will be described withparticular reference thereto, but it is also contemplated to apply tomolding of the intermediate layer 16. The preferred embodiment ball 10includes one or more deep dimples 18 that extend through at least thecover layer 14. The deep dimples 18 extend to, or through, theintermediate layer 16. The deep dimples may further extend into the core12. It will be appreciated that in the event the core is liquid, thedeep dimples will not extend to the core.

As noted, the present invention relates to various molding assembliesand techniques for forming a golf ball having one or more deep dimplesalong an outer surface of the golf ball. The deep dimples extend throughthe outermost cover layer of the ball, to or into or through one or morecomponents underneath the outermost cover layer. As explained herein,the deep dimples result from one or more outwardly extending projectionsor protrusions that are provided in a molding chamber used for moldingthe final ball. The protrusions generally have a height greater thanother raised regions along the molding surface that form conventionaldimples along the ball exterior.

Turning now to FIG. 2, a perspective view of a preferred embodimentmolding assembly in accordance with the current invention is shown. Aspreviously noted, complete and timely mixing of two or more constituentmaterials is important when using a RIM process. The preferredembodiment molding assembly 20 provides such mixing as a result of itsunique design and configuration. An injection machine, as known in theart, is connected to the preferred embodiment molding assembly 20 whichcomprises an upper half 22A and a lower half 22B. As will beappreciated, the upper and lower halves 22A and 22B are preferablyformed from a metal or suitable material. A mixing chamber may, as knownin the art, precede the molding assembly 20 if desired. In a furtheraspect of the present invention, the molding assembly 20 is utilized asfollows. A core 12 (referring to FIG. 1) is positioned within a centralcavity formed from two hemispherical depressions 24A and 24B defined inopposing faces of the upper half and lower half 22A and 22B,respectively, of the molding assembly 20. As will be appreciated, whenthe upper and lower halves 22A and 22B are closed, and the cavities 24Aand 24B are aligned with each other, the resulting cavity has aspherical configuration. If the molding assembly is for molding a coverlayer, each of the hemispherical cavities 24A and 24B defines aplurality of raised regions that, upon molding a cover layer therein,will result in corresponding dimples on the cover layer.

Each upper and lower half 22A and 22B of the preferred embodimentmolding assembly 20 defines an adapter portion 26A and 26B to enable themolding assembly 20 to connect to other process equipment as mentionedabove and leads to a material inlet channel 28A and 28B as illustratedin FIG. 2. As will be understood, upon closing the upper and lowerhalves 22A and 22B of the molding assembly 20, the separate halves ofadapter portion 26A and 26B are aligned with each other and create amaterial flow inlet within the molding assembly. And, each upper andlower half 22A and 22B of the assembly 20 further defines flow channels28A and 28B, 30A and 30B and 32A and 32B which create a comprehensiveflow channel within the molding assembly when the upper and lower halves22A and 22B are closed. Specifically, the material flow inlet channelportion 28A, 28B receives the constituent materials from the adapterportion 26A and 26B and directs those materials to aturbulence-promoting portion of the channel 30A, 30B which is configuredto form at least one fan gate. The upper and lower mold halves 22A and22B include complimentary turbulence-promoting peanut after-mixerchannel portions 30A and 30B, respectively. It will be appreciated thatupon closing the upper and lower halves 22A and 22B of the moldingassembly 20, the channel portion 30A and 30B defines a region of theflow channel that is generally nonlinear and includes a plurality ofbends and at least one branching intersection generally referred toherein as an after-mixer gate. Each after-mixer channel portion 30A, 30Bis designed to direct material flow along an angular or tortuous path.As will be described in more detail below, when material reaches aterminus of angular flow in one plane of the flow channel in one half,the material flows in a transverse manner to a corresponding after-mixerchannel portion in the opposing half. Thus, when the constituentmaterials arrive at the after-mixer defined by the channel portion 30Aand 30B, turbulent flow is promoted, forcing the materials to continueto mix within the molding assembly 20. This mixing within the moldingassembly 20 provides for improved overall mixing of the constituentmaterials, thereby resulting in a more uniform and homogeneouscomposition for the cover 14.

With continuing reference to FIGS. 3 and 4, views 3—3 and 4—4 from FIG.2, respectively, are provided. These views illustrate additional detailsof the present invention as embodied in the mold upper and lower halves22A and 22B. The material inlet channel 28A and 28B allows entry of theconstituents which are subsequently directed through the mix-promotingchannel portion 30A and 30B, which forms the after-mixer, then throughthe connecting channel portion 32A and 32B and to the fan gate portion34A and 34B which leads into the cavity 24A and 24B. The final channelportion 34A and 34B may be defined in several forms extending to thecavity 24A and 24B, including corresponding or complimentary paths whichmay be closed (34A) or open (34B) and of straight, curved or angular(34A, 34B) shape.

With continuing reference to FIGS. 3 and 4, at least one protrusion 36preferably extends into the central cavity 24A and 24B. This at leastone protrusion extends from the molding surface into the molding cavity24A and 24B and supports a golf ball core, such as core 12, orintermediate ball assembly. The preferred dimensions, configuration, andorientation of the protrusion(s) are explained in greater detail herein.It is these protrusion(s) that form one or more deep dimple(s) in theouter surface of a golf ball and which relate to another aspect of thepresent invention. In typical injection molding, many retractable pins,often four, six or more, are used to centrally position and retain thecore 12 in the molding cavity. It has been discovered that because ofthe reduced process pressure involved in RIM, fewer supportingstructures are necessary in the molding assembly 20 to centrally locatethe core 12 in the central cavity 24A and 24B. For example, only threeprotrusions 36 or less may be necessary per mold half. For someembodiments, it is preferred to utilize six protrusions per mold half.The use of fewer supporting structures reduces the cost of the toolingand reduces problems such as defacement and surface imperfections causedby retractable pins. The protrusions 36 are preferably provided atdifferent locations in the molding assembly 20 and extend into differentportions of the central cavity formed by the hemispherical cavities 24A,24B. A channel leading from the cavity 24A and 24B may be provided aseither a cavity venting channel or an overflow channel or dump well asknown in the art. As shown in FIG. 2, a dump well 31A, 31B is providedin the corresponding molds. A dump well vent 33A, 33B providescommunication between the dump well and mold exterior. A venting channel29A, 29B is defined in the molds and provides communication between thecentral cavity 24A, 24B and the dump well. It will be appreciated thatwhen the upper and lower halves 22A and 22B are closed, the respectiveportions of the channel align with one another to form the venting oroverflow channel.

Turning now to FIG. 5, a perspective view of the molding assembly 20illustrates the details of material flow and mixing provided by thecurrent invention. The body halves 22A and 22B are shown in an openposition, i.e., removed from one another, for purposes of illustrationonly. It will be appreciated that the material flow described belowtakes place when the halves 22A and 22B are closed. The adapter portion26A, 26B leads to the inlet flow channel 28A, 28B which typically has auniform circular cross section of 360°. The flowing material proceedsalong the inlet channel 28A, 28B until it arrives in a locationapproximately at a plane designated by line C—C. At this region, thematerial is forced to split apart by a branching intersection 38A and38B. Each half of the branching intersection 38A and 38B is divergent,extending in a direction generally opposing the other half. For example,portion 38A extends upward and 38B extends downward relative to theinlet channel 28A, 28B as shown. Each half of the branching intersection38A and 38B, in the illustrated embodiment, is semicircular, or about180° in curvature. The separated material flows along each half of thebranching intersection 38A and 38B until it reaches a respective wall,40A and 40B.

At each first wall 40A and 40B, the material can no longer continue toflow within the plane of the closed mold, i.e., the halves 22A and 22Bbeing aligned with one another. To aid the present description it willbe understood that in closing the mold, the upper half 22A is orienteddownward (referring to FIG. 5) so that it is generally parallel with thelower half 22B. The orientation of the halves 22A and 22B in such aclosed configuration is referred to herein as lying in an x-y plane. Asexplained in greater detail herein, the configuration of the presentinvention after-mixer provides one or more flow regions that aretransversely oriented to the x-y plane of the closed mold. Hence, thesetransverse regions are referred to as extending in a z direction.

Specifically, at the first wall 40A the material flows from a point 1 inone half 22A to a corresponding point 1 in the other half 22B. Point 1in half 22B lies at the commencement of a first convergent portion 42B.Likewise, at the first wall 40B the material flows from a point 1 in onehalf 22B to a corresponding point 1 in the other half 22A. The point 1in half 22A lies at the commencement of a first convergent portion 42A.The first convergent portion 42A and 42B brings the material to a firstcommon area 44A and 44B. In the shown embodiment, each first convergentportion is parallel to each first diverging branching intersection topromote a smooth material transfer. For example, the portion 42A isparallel to the portion 38A, and the portion 42B is parallel to theportion 38B.

With continuing reference to FIG. 5, the flowing material arrives at thefirst common area 44A and 44B, which has a full circular, i.e., 360degrees, cross section when the halves 22A and 22B are closed.Essentially, the previously separated material is rejoined in the firstcommon area 44A and 44B. A second branching intersection 46A and 46Bwhich is divergent then forces the material to split apart a second timeand flow to each respective second wall 48A and 48B. As with the firstwall 40A and 40B, the material, upon reaching the second wall 48A and48B can no longer flow in an x-y plane and must instead move in atransverse z-direction. For example, at the Wall 48A, the material flowsfrom a point ″2 in one half 22A to a corresponding point ″2 in the otherhalf 22B, which lies in a second convergent portion 50B. The materialreaching the wall 48B flows from a point $2 in one half 22B to acorresponding point $2 in the other half 22A, which lies in a secondconvergent portion 50A.

In the shown embodiment, each second convergent portion 50A and 50B, isparallel to each second diverging branching intersection 46A and 46B.For example, the portion 50A is parallel to the portion 46A and theportion 50B is parallel to the portion 46B. The second convergentportion 50A and 50B forces the material into a second common area 52Aand 52B to once again rejoin the separated material. As with the firstcommon area 44A and 44B, the second common area 52A and 52B has a fullcircular cross section.

After the common area 52A and 52B, a third branching intersection 54Aand 54B again diverges, separating the material and conveying it indifferent directions. Upon reaching each respective third wall, i.e.,the wall 56A in the portion 54A and the wall 56B in the portion 54B, thematerial is forced to again flow in a transverse, z-direction from theplanar x-y direction. From a point 3 at the third wall 56A in one half22A, the material flows to a corresponding point 3 in the other half22B, which lies in a third convergent portion 58B. Correspondingly, froma point 3 at third wall 56B in one half 22B, the material flows to acorresponding point 3 in the other half 22A, which is in a thirdconvergent portion 58A.

The turbulence-promoting after-mixer structure 30A and 30B ends with athird convergent portion 58A and 58B returning the separated material tothe connecting flow channel 32A and 32B. The connecting channel 32A and32B is a common, uniform circular channel having a curvature of 360degrees. Once the material enters the connecting channel portion 32A and32B, typical straight or curved smooth linear flow recommences.

By separating and recombining materials repeatedly as they flow, thepresent invention provides for increased mixing of constituentmaterials. Through the incorporation of split channels and transverseflow, mixing is encouraged and controlled while the flow remainsuniform, reducing back flow or hanging-up of material, thereby reducingthe degradation often involved in non-linear flow. Particular note ismade of the angles of divergence and convergence of the after-mixerportions 38A and 38B, 42A and 42B, 46A and 46B, 50A and 50B, 54A and 54Band 58A and 58B, as each extends at the angle of about 30 degrees to 60degrees from the centerline of the linear inlet flow channel 28A, 28B.This range of angles allows for rapid separation and re-convergencewhile minimizing back flow. In addition, each divergent branchingportion and converging portion 38A and 38B, 42A and 42B, 46A and 46B,50A and 50B, 54A and 54B and 58A and 58B extends from the centerline ofthe linear inlet flow channel 28A, 28B for a distance of one to threetimes the diameter of the channel 28A, 28B before reaching itsrespective wall 40A and 40B, 48A and 48B and 56A and 56B. Further noteis made of the common areas 44A and 44B and 52A and 52B. These areas aredirectly centered about a same linear centerline which extends from theinlet flow channel portion 28A, 28B to the commencement of theconnecting flow channel portion 32A, 32B. As a result, the common areas44A and 44B and 52A and 52B are aligned linearly with the channelportions 28A, 28B and 32A, 32B, providing for more consistent, uniformflow. While several divergent, convergent, and common portions areillustrated, it is anticipated that as few as one divergent andconvergent portion or as many as ten to twenty divergent and convergentportions may be used, depending upon the application and materialsinvolved.

FIG. 6 depicts the turbulence-promoting after-mixer channels 30A, 30Bfrom a side view when the molding assembly 20 is closed. As describedabove, upon closure, the upper half 22A and the lower half 22B meet,thereby creating the turbulence-promoting after-mixer along the regionof the channel portions 30A and 30B. The resulting flow pathway causesthe constituent materials flowing therethrough to deviate from astraight, generally linear path to a nonlinear turbulence-promotingpath. The interaction and alignment of the divergent branchingintersections 38A and 38B, 46A and 46B, 54A and 54B (referencing back toFIG. 5), the convergent portions 42A and 42B, 50A and 50B, 58A and 58B,and the common portions 44A and 44B, and 52A and 52B, also as describedabove, is shown in detail.

In a particularly preferred embodiment, the after-mixer includes aplurality of bends or arcuate portions that cause liquid flowing throughthe fan gate to not only be directed in the same plane in which the flowchannel lies, but also in a second plane that is perpendicular to thefirst plane. It is most preferable to utilize an after-mixer with bendssuch that liquid flowing therethrough travels in a plane that isperpendicular to both the previously noted first and second planes. Thisconfiguration results in relatively thorough and efficient mixing due tothe rapid and changing course of direction of liquid flowingtherethrough.

The configuration of the mold channels may take various forms. One suchvariation is shown in FIG. 7. Reference is made to the lower mold half22B for the purpose of illustration, and it is to be understood that theupper mold half 22A (not shown) comprises a complimentary configuration.The adapter portion 26B leads to the inlet flow channel 28B which leadsto the turbulence-promoting channel portion 30B. However, instead of theadapter 26B and the channels 28B and 30B being spaced apart from thecentral cavity 24B, they are positioned approximately in line with thecentral cavity 24B, eliminating the need for the connecting channelportion 32B to be of a long, curved configuration to reach the fan gateportion 34B. Thus, the connecting channel 32B is a short, straightchannel, promoting a material flow path which may be more desirable forsome applications. The flow channels and the central cavity may bearranged according to other forms similar to those shown, which mayoccur to one skilled in the art, as equipment configurations andparticular materials and applications dictate. FIG. 7 also illustratesone or more nonretractable protrusions 36 in the molding chamber.

In the above-referenced figures, the channels 30A and 30B are depictedas each comprising a plurality of angled bends or turns. Turning now toFIG. 8, the channels are not limited to the angled bend-type fan gateconfiguration and include any turbulence-promoting design located in aregion 59B between the adapter portion 26B and the cavity 24B. Again,reference is made to the lower mold half 22B for the purpose ofillustration, and it is to be understood that the upper mold half 22A(not shown) is complimentary to the lower mold half 22B. The channels inthe turbulence-promoting region 59A (not shown) and 59B could be formedto provide one or more arcuate regions such that upon closure of theupper and lower mold halves 22A and 22B, the flow gate has, for example,a spiral or helix configuration. Regardless of the specificconfiguration of the channels in the turbulence promoting portion 59Aand 59B, the shape of the resulting flow gate insures that the materialsflow through the turbulence-promoting region and thoroughly mix witheach other, thereby reducing typical straight laminar flow andminimizing any settling in a low-flow area where degradation of flow mayoccur. Preferably, the shape and configuration of the flow channel issuch that the velocity of the materials flowing therethrough isgenerally constant at different locations along the channel. And, aspreviously noted, such flow characteristics and thorough mixing of thematerials has been found to lead to greater consistency and uniformityin the final physical properties and characteristics of the resultinggolf ball layer or component. FIG. 8 further illustrates one or moreprotrusions 36 in the molding chamber.

As shown in FIG. 9, the turbulence-promoting region 59A (not shown) and59B may be placed in various locations in the upper and lower moldhalves 22A (not shown) and 22B. As mentioned above, theturbulence-promoting region 59B and the other flow channel portions 28B,32B, and 34B may be arranged so as to create an approximately straightlayout between the adapter portion 26B and the central cavity 24B. Byallowing flexibility in the location of the turbulence-promoting region59B and the other channel portions 28B, 32B and 34B, as well as theadapter 26B and the central cavity 24B, optimum use may be made of thepresent invention in different applications. FIG. 9 also illustrates oneor more protrusions 36 in the molding chamber.

Gases, including air and moisture, are often present in a RIM processand create undesirable voids in the molded cover 14. Venting of centralcavity 24A, 24B reduces voids by removing these gases. Through the useof venting, a cover 14 is provided that is significantly more free fromvoids or other imperfections than a cover produced by a non-vented RIMprocess.

A preferred method of making a golf ball in accordance with the presentinvention is illustrated in FIG. 10. A golf ball core 12 made bytechniques known in the art is obtained, illustrated as step 70. Thecore 12 is preferably positioned within a mold having ventingprovisions, after-mixers, and fan gates as described herein. This isillustrated as step 72. It is preferred that the core 12 is supported ona plurality of the previously described protrusions 36 that form deepdimples in the final ball. This is shown as step 74. The mold is thenclosed. This is illustrated as step 75. The cover layer 14 is moldedover the core 12 by RIM as step 76. If venting of gases from the moldingcavity is desired, such gases are preferably vented as previouslydescribed. This is designated as step 78. Should increased removal ofgases be desired, the venting of step 78 is enhanced by providing avacuum connection as known in the art to the venting channel. When themolding is complete, the golf ball 10 is removed from the mold, as shownby steps 79 and 80.

In accordance with conventional molding techniques, the preferredembodiment molding processes described herein may utilize one or moremold release agents to facilitate removal of the molded layer orcomponent from the mold.

A golf ball manufactured according the preferred method described hereinexhibits unique characteristics. Golf ball covers made throughcompression molding and traditional injection molding include balata,ionomer resins, polyesters resins and polyurethanes. The selection ofpolyurethanes which can be processed by these methods is limited.Polyurethanes are often a desirable material for golf ball coversbecause balls made with these covers are potentially more resistant toscuffing and resistant to deformation than balls made with covers ofother materials. The current invention allows processing of a wide arrayof grades of polyurethane through RIM which was not previously possibleor commercially practical utilizing either compression molding ortraditional injection molding. It is anticipated that other urethaneresins such as Bayer® MP-7500, Bayer® MP-5000, Bayer® aliphatic or lightstable resins, and Uniroyal® aliphatic and aromatic resins may be used.For example, utilizing the present invention method and Bayer® MP-10000polyurethane resin, a golf ball with the properties described below hasbeen provided. Also, depending upon the application, BASF aromatic oraliphatic resins may be used.

Some of the unique characteristics exhibited by a golf ball according tothe present invention include a thinner cover without the accompanyingdisadvantages otherwise associated with relatively thin covers such asweakened regions at which inconsistent compositional differences exist.A traditional golf ball cover typically has a total thickness in therange of about 0.060 inches to 0.080 inches. A golf ball of the presentinvention may utilize a cover having a thickness of from about 0.002inches to about 0.100 inches, more preferably from about 0.005 inches toabout 0.075 inches, more preferably from about 0.010 inches to about0.050 inches, and most preferably from about 0.015 inches to about 0.050inches. This reduced cover thickness is often a desirablecharacteristic. It is contemplated that thinner layer thicknesses arepossible using the present invention.

Because of the reduced pressure involved in RIM as compared totraditional injection molding, an outer cover or any other layer of thepresent invention golf ball is more dependably concentric and uniformwith the core of the ball, thereby improving ball performance. That is,a more uniform and reproducible geometry is attainable by employing thepresent invention.

The present invention also provides a golf ball in which at least onecover or core layer is a fast-chemical-reaction-produced component. Thiscomponent comprises at least one material selected from the groupconsisting of polyurethane, polyurea, polyurethane ionomer, epoxy, andunsaturated polyesters, and preferably comprises polyurethane. Theinvention also includes a method of producing a golf ball which containsa fast-chemical-reaction-produced component. A golf ball formedaccording to the invention preferably has a flex modulus in the range offrom about 5 to about 310 kpsi, a Shore D hardness in the range of fromabout 20 to about 90, and good durability. Particularly preferred formsof the invention also provide for a golf ball with afast-chemical-reaction-produced cover having good scuff resistance andcut resistance. As used herein, “polyurethane and/or polyurea” isexpressed as “polyurethane/polyurea”.

A particularly preferred form of the invention is a golf ball with acover comprising polyurethane, the cover including from about 5 to about100 weight percent of polyurethane formed from recycled polyurethane.

The method of the invention is particularly useful in forming golf ballsbecause it can be practiced at relatively low temperatures andpressures. The preferred temperature range for the method of theinvention is from about 50° F. to about 250° F. and preferably fromabout 120° F. to about 180° F. when the component being producedcontains polyurethane. Preferred pressures for practicing the inventionusing polyurethane-containing materials are 200 psi or less and morepreferably 100 psi or less. The method of the present invention offersnumerous advantages over conventional slow-reactive process compressionmolding of golf ball covers. The method of the present invention resultsin molded covers in a demold time of 10 minutes or less. An excellentfinish can be produced on the ball.

The method of the invention also is particularly effective when recycledpolyurethane or other polymer resin, or materials derived by recyclingpolyurethane or other polymer resin, is incorporated into the product.

As indicated above, the fast-chemical-reaction-produced component can beone or more cover and/or core layers of the ball. When a polyurethanecover is formed according to the invention, and is then covered with apolyurethane top coat, excellent adhesion can be obtained. The adhesionin this case is better than adhesion of a polyurethane coating to anionomeric cover. This improved adhesion can result in the use of athinner top coat, the elimination of a primer coat, and the use of agreater variety of golf ball printing inks beneath the top coat. Theseinclude but are not limited to typical inks such as one componentpolyurethane inks and two component polyurethane inks.

More specifically, the preferred method of forming afast-chemical-reaction-produced component for a golf ball according tothe invention is by RIM. In this approach, highly reactive liquids areinjected into a closed mold, mixed usually by impingement and/ormechanical mixing and secondarily mixed in an in-line device such as apeanut mixer, where they polymerize primarily in the mold to form acoherent, one-piece molded article. The RIM processes usually involve arapid reaction between one or more reactive components such aspolyether—or polyester—polyol, polyamine, or other material with anactive hydrogen, and one or more isocyanate—containing constituents,often in the presence of a catalyst. The constituents are stored inseparate tanks prior to molding and may be first mixed in a mix headupstream of a mold and then injected into the mold. The liquid streamsare metered in the desired weight to weight ratio and fed into animpingement mix head, with mixing occurring under high pressure, e.g.,1500 to 3000 psi. The liquid streams impinge upon each other in themixing chamber of the mix head and the mixture is injected into themold. One of the liquid streams typically contains a catalyst for thereaction. The constituents react rapidly after mixing to gel and formpolyurethane polymers. Polyureas, epoxies, and various unsaturatedpolyesters also can be molded by RIM.

As previously noted, RIM differs from non-reaction injection molding ina number of ways. The main distinction is that in RIM a chemicalreaction takes place in the mold to transform a monomer or adducts topolymers and the components are in liquid form. Thus, a RIM mold neednot be made to withstand the pressures which occur in a conventionalinjection molding. In contrast, injection molding is conducted at highmolding pressures in the mold cavity by melting a solid resin andconveying it into a mold, with the molten resin often being at about 150to about 350° C. At this elevated temperature, the viscosity of themolten resin usually is in the range of 50,000 to about 1,000,000centipoise, and is typically around 200,000 centipoise. In an injectionmolding process, the solidification of the resins occurs after about 10to 90 seconds, depending upon the size of the molded product, thetemperature and heat transfer conditions, and the hardness of theinjection molded material. Subsequently, the molded product is removedfrom the mold. There is no significant chemical reaction taking place inan injection molding process when the thermoplastic resin is introducedinto the mold. In contrast, in a RIM process, the chemical reactiontypically takes place in less than about 2 minutes, preferably in underone minute, and in many cases in about 30 seconds or less.

If plastic products are produced by combining components that arepreformed to some extent, subsequent failure can occur at a location onthe cover which is along the seam or parting line of the mold. Failurecan occur at this location because this interfacial region isintrinsically different from the remainder of the cover layer and can beweaker or more stressed. The present invention is believed to providefor improved durability of a golf ball cover layer by providing auniform or seamless cover in which the properties of the cover materialin the region along the parting line are generally the same as theproperties of the cover material at other locations on the cover,including at the poles. The improvement in durability is believed to bea result of the fact that the reaction mixture is distributed uniformlyinto a closed mold. This uniform distribution of the injected materialsreduces or eliminates knit-lines and other molding deficiencies whichcan be caused by temperature difference and/or reaction difference inthe injected materials. The process of the invention results ingenerally uniform molecular structure, density and stress distributionas compared to conventional injection-molding processes.

The fast-chemical-reaction-produced component has a flex modulus of fromabout 1 to about 310 kpsi, more preferably from about 1 to about 100kpsi, and most preferably from about 2 to about 50 kpsi. The subjectcomponent can be a cover with a flex modulus which is higher than thatof the centermost component of the cores, as in a liquid center core andsome solid center cores. Furthermore, thefast-chemical-reaction-produced component can be a cover with a flexmodulus that is higher than that of the immediately underlying layer, asin the case of a wound core. The core can be one piece or multi-layer,each layer can be either foamed or unfoamed, and density adjustingfillers, including metals, can be used. The cover of the ball can beharder or softer than any particular core layer.

The fast-chemical-reaction-produced component can incorporate suitableadditives and/or fillers. When the component is an outer cover layer,pigments or dyes, accelerators and UV stabilizers can be added. Examplesof suitable optical brighteners which probably can be used includeUvitex? and Eastobrite? OB-1. An example of a suitable white pigment istitanium dioxide. Examples of suitable and UV light stabilizers areprovided in commonly assigned U.S. Pat. No. 5,494,291. Fillers which canbe incorporated into the fast-chemical-reaction-produced cover or corecomponent include those listed below in the definitions section.Furthermore, compatible polymeric materials can be added. For example,when the component comprises polyurethane and/or polyurea, suchpolymeric materials include polyurethane ionomers, polyamides, etc.

A golf ball core layer formed from a fast-chemical-reaction-producedmaterial according to the present invention typically contains 0 to 20weight percent of such filler material, and more preferably 1 to 15weight percent. When the fast-chemical-reaction-produced component is acore, the additives typically are selected to control the density,hardness and/or COR.

A golf ball inner cover layer formed from afast-chemical-reaction-produced material according to the presentinvention typically contains 0 to 60 weight percent of filler material,more preferably 1 to 30 weight percent, and most preferably 1 to 20weight percent.

A golf ball outer cover layer formed from afast-chemical-reaction-produced material according to the presentinvention typically contains 0 to 20 weight percent of filler material,more preferably 1 to 10 weight percent, and most preferably 1 to 5weight percent.

Catalysts can be added to the RIM polyurethane system starting materialsas long as the catalysts generally do not react with the constituentwith which they are combined. Suitable catalysts include those which areknown to be useful with polyurethanes and polyureas.

The reaction mixture viscosity should be sufficiently low to ensure thatthe empty space in the mold is completely filled. The reactant materialsgenerally are preheated to about 80° F. to about 200° F. and preferablyto 100° F. to about 180° F. before they are mixed. In most cases it isnecessary to preheat the mold to, e.g., from about 80° F. to about 200°F., to provide for proper injection viscosity.

As indicated above, one or more cover layers of a golf ball can beformed from a fast-chemical-reaction-produced material according to thepresent invention.

Referring to FIG. 11, another preferred embodiment golf ball having acover comprising a RIM polyurethane is shown. The golf ball 110 includesa polybutadiene core 112 and a polyurethane cover 114 formed by RIM. Thegolf ball 110 defines a plurality of dimples 116 along its outersurface. Preferably, the ball 110 also defines one or more deep dimples118 as described in greater detail herein.

Referring now to FIG. 12, the golf ball 110 having a core comprising aRIM polyurethane is shown. The golf ball 110 has a RIM polyurethane core112, and a RIM polyurethane cover 114. The golf ball 110 defines aplurality of dimples 116 along its outer surface. Preferably, the ball110 also defines one or more deep dimples 118 as described in greaterdetail herein.

Referring to FIGS. 13 and 14, a multi-layer golf ball 210 is shown witha solid core 212 containing recycled RIM polyurethane, a mantle coverlayer comprising RIM polyurethane 213, and an outer cover layer 214comprising ionomer or another conventional golf ball cover material.Non-limiting examples of multi-layer golf balls according to theinvention with two cover layers include those with RIM polyurethanemantles having a thickness of 0.01 to 0.20 inches, or thinner, and aShore D hardness of 20 to 80, covered with ionomeric or non-ionomericthermoplastic, balata or other covers having a Shore D hardness of 20 to80 and a thickness of 0.010 to 0.20 inches. The golf ball 210 defines aplurality of dimples 216 along its outer surface. Preferably, the ball210 also defines one or more deep dimples 218 as described in greaterdetail herein.

Referring again to FIGS. 11 and 12, those figures illustrate a preferredembodiment golf ball 110 produced in accordance with the presentinvention. One or more of the deep dimples 120, and preferably two ormore of the dimples 120, and more preferably three or more of thedimples per hemisphere, extend into the core 112 disposed underneath thecover layer 114. These dimples are herein referred to as deep dimples.

The preferred embodiment golf ball 210 shown in FIGS. 13 and 14comprises a core 212 having an inner cover layer 213 disposed thereonand an outer cover layer 214 formed about the inner cover layer 213. Thecover layers 213 and 214 define a plurality of dimples 216 along theouter surface of the outer cover layer 160. One or more of the dimples,and preferably two or more of the dimples, and more preferably three ormore of the dimples per hemisphere, extend entirely through the outercover layer 214 and at least partially into or to the inner cover layer213. These dimples, which extend through the outer cover layer, areagain referred to herein as deep dimples and shown in FIG. 13 as dimples218.

The deep dimples can be circular, non-circular, a combination ofcircular and non-circular, or any other shape desired. They may be ofthe same or differing shape, such as a circular larger dimple having anoval smaller dimple within the circular dimple, or an oval larger dimplehaving a circular or other shape within the larger dimple. The dimplesdo not have to be symmetrical.

Providing deep dimples formed in multiple layers allows the dimple depthto be spread over two or more layers. FIG. 13 illustrates deep dimple220 formed in both the inner cover layer and the outer cover layer. Theinner portion of the dimple 220 is formed in the inner cover layer 213,and the outer portion of the dimple 220 is formed in the outer coverlayer 214. For a two-piece ball, dimples may be formed in the core andthe single cover layer in the same way as previously described.Additionally, dimples may be formed in more than two cover and/or corelayers if desired.

In another preferred embodiment, a multi-layer golf ball is producedthat has one or more deep dimples that protrude into the ball through atleast one layer, such as an outer cover layer. In a further preferredembodiment, the deep dimple protrudes through at least two layers. Thedimples of the at least two layers are configured with the samegeometric coordinates (that is, the approximate center of the bothdimples would be in the same location, and so the dimples are concentricwith respect to each other), producing a golf ball having a dimpledlayer over a dimpled layer. This allows for much thinner layers withtraditional dimples. The dimples of one or more inner layers may be ofvarying depths, diameters and radii, yet still aligned with the dimplesof the outer layer. This also allows for a dimple within a dimple, wherethere is a smaller dimple in at least one inner or mantle layer that iswithin a larger diameter dimple in the outer layer, such as the dimplesshown in FIGS. 15 to 18.

FIGS. 15 to 18 illustrate a deep dimple that is a dual radius dimple, ora dimple within a dimple. One advantage of a dual radius dimple is thatthe deeper part of the dual radius may be filled in with a coating orother material. This provides an effective method for forming dimpledepths to a desired value as compared to other methods of dimpleformation. The dimple shape may be any shape desired, and each dimplemay be the same or different shape. Preferably, the depth of the secondor deepest portion of the dual radius dimple may be expressed as apercentage of the total depth of the dimple. Specifically, the region orportion of the dimple which extends to the outermost surface of the ballmay be referred to herein as the “major” dimple. And, likewise, theportion of the dimple which extends to the deepest portion or depth ofthe dimple can be referred to herein as the “minor” dimple. Accordingly,the preferred depth of the major dimple is approximately from about 40%to about 80% of the overall dimple depth. Accordingly, the preferreddepth of the minor dimple is approximately 20% to about 60% of theoverall dimple depth. The depth being measured from the chord of themajor dimple to the bottom of the minor dimple. With regard todiameters, the preferred diameter of the minor dimple is from about 10%to about 70% of the diameter of the major dimple.

FIG. 15 is a cross-sectional detail illustrating a portion of apreferred embodiment golf ball produced in accordance with the presentinvention. This preferred embodiment golf ball 310 comprises a core 320having a cover layer 330 formed thereon. The cover layer defines atleast one deep dimple 340 along its outer surface 335. As previouslydescribed, it is preferred that one or more (preferably two or more,more preferably three or more per hemisphere) of the dimples extendsentirely through the cover layer and into the core disposed underneaththe cover layer. FIG. 15 illustrates a deep dimple defined by twodifferent curvatures. Referring to FIG. 15, a first radius R₁ definesthe portion of the dimple from the outer surface 335 of the golf ball310 to a point at which the deep dimple extends into a layer underneaththe cover layer. At this point, the curvature of the dimple changes andis defined by radius R₂. Preferably, R₁, is from about 0.130 inches toabout 0.190 inches, and most preferably, R₁, is from about 0.140 toabout 0.180 inches. For some embodiments, R₁ ranges from about 0.100inches to about 1.000 inch, and most preferably from about 0.200 inchesto about 0.800 inches. Preferably, R₂ is from about 0.025 inches toabout 0.075 inches, and most preferably, R₂ is about 0.050 to about0.065 inches. For some embodiments, R₂ ranges from about 0.002 inches toabout 0.500 inches, and most preferably from about 0.010 inches to about0.200 inches. The overall diameter or span of the dimple 340 isdesignated herein as D₁. The diameter or span of the portion of thedimple that extends into the layer underneath the outer cover layer isdesignated herein as D₂. Preferably, D₁ is from about 0.030 inches toabout 0.250 inches, more preferably from about 0.100 inches to about0.186 inches, and most preferably, D₁ is about 0.146 inches to about0.168 inches. For some embodiments, D₁ ranges from about 0.100 inches toabout 0.250 inches, and most preferably D₁ is about 0.140 inches toabout 0.180 inches. Preferably D₂ is from about 0.020 inches to about0.160 inches, more preferably from about 0.030 inches to about 0.080inches, and most preferably, D₂ is about 0.056 inches. For someembodiments, D₂ is from about 0.040 inches to about 0.060 inches.Accordingly, the overall depth of the deep dimple portion that isdefined by R₁ is designated herein as H₁ and the depth or portion of thedimple that is defined by R₂ is designated herein as H₂. Preferably, H₁is from about 0.005 inches to about 0.135 inches, more preferably fromabout 0.005 to about 0.025 inches, more preferably from about 0.010inches to about 0.015 inches, and most preferably, H₁ is about 0.015inches. For some embodiments, H₁ is from about 0.005 inches to about0.015 inches. H₂ may range from about 0.005 inches to about 0.135inches, and more preferably from about 0.005 to about 0.050 inches.Preferably, H₂ ranges from about 0.005 inches to about 0.030 inches andis about 0.010 inches. For some embodiments, H₂ is from about 0.005inches to about 0.015 inches.

Referring to FIG. 16, another preferred embodiment golf ball 410 isillustrated. In this version of the present invention, a golf ball 410comprises a core 420 and a cover layer 430 formed thereon. The coverlayer 430 defines at one deep dimple 440 along the outer surface 435 ofthe golf ball 410. As can be seen, the dimple 440 is defined by twodifferent curvatures, each of which is defined by radii R₂ and R₁ aspreviously described with respect to FIG. 15. The other parameters D₁,D₂, H₁, and H₂ are as described with respect to FIG. 15. FIG. 16illustrates an embodiment in which the dimple 440 extends to the core420 and not significantly into the core. In contrast, the versionillustrated in FIG. 15 is directed to a dimple configuration in which adimple extends significantly into the underlying core.

FIG. 17 illustrates a preferred embodiment golf ball 510 comprising acore 520, a mantle or inner cover layer 550, and an outer cover layer560. The outer cover layer 560 and inner cover layer 550 define at leastone deep dimple 540 along the outer surface 535 of the ball 510. Thedimple 540 is defined by two different regions or two curvatures, eachof which is in turn defined by radii R₂ and R₁. The other parameters D₁,D₂, H₁, and H₂ are as described with respect to FIG. 15. As can be seenin FIG. 17, the dimple 540 extends entirely through the outer coverlayer 560 and into the inner cover layer or mantle layer 550.

FIG. 18 illustrates another preferred embodiment golf ball 610 inaccordance with the present invention. The golf ball 610 comprises acore 620 having disposed thereon an inner cover layer or mantle layer650 and an outer cover layer 660. Defined along the perimeter or outerperiphery of the ball 610 is at least one deep dimple 640. The dimple640 is defined along the outer surface 635 of the ball 610. The dimple640 has two different regions or curvatures each defined by radii R₂ andR₁. The other parameters D₁, D₂, H₁, and H₂ are as described withrespect to FIG. 15. The version illustrated in FIG. 18 reveals a dimple640 that does not significantly extend into the mantle layer or innercover layer 650. Instead, the dimple 640 only extends to the outermostregion of the mantle layer or inner cover layer 650.

An important characteristic of dimple configuration is the volume ratio.The volume ratio is the sum of the volume of all dimples taken below achord extending across the top of a dimple, divided by the total volumeof the ball. The volume ratio is a critical parameter for ball flight. Ahigh volume ratio generally results in a low flying ball. And a lowvolume ratio often results in a high-flying ball. A preferred volumeratio is about 1%. The balls of the present invention however may beconfigured with greater or lesser volume ratios.

The number and/or layout of dimples will not necessarily change thecoverage, i.e. surface area. A typical coverage for a ball of thepresent invention is about 60% to about 90% and preferably about 83.8%.In other embodiments, this preferred coverage is about 84% to about 85%.These percentages are the percent of surface area of the ball occupiedby dimples. It will be appreciated that the present invention golf ballsmay exhibit coverages greater or less than that amount.

For configurations utilizing dimples having two or more regions ofdifferent curvature, i.e. dimple within a dimple, there is less impacton the volume ratio than the use of deep dimples. If there are enough ofeither dimples within dimples or deep dimples, the aerodynamics of theball will eventually be impacted.

The optimum or preferred number of deep dimples utilized per ballvaries. It is the amount necessary to secure or center the core or coreand cover layer(s) during molding without adversely affecting theaerodynamics of the finished ball. However, the present inventionincludes the use of a relatively large number of deep dimples. That is,although most of the focus of the present invention is directed to theuse of only a few deep dimples per golf ball, i.e. from 2 to 6, theinvention includes the use of a significantly greater number such asfrom about 50 to about 250. It is also contemplated that for someapplications, it may be desirable to form all, or nearly all, dimples ona golf ball as deep dimples such as, for example, from about 50 to about500.

In certain golf ball embodiments, it may be desirable to form aparticular proportion of the dimples along the outer surface of the golfball as deep dimples. The proportion selected may depend uponaesthetics, aerodynamic effects, marketability factors, ballperformance, manufacturing, or other factors. Generally, the proportionof dimples that may be formed as deep dimples may be all, substantiallyall, a majority, half, a minority, or a minor number.

More specifically, in certain embodiments, it is desirable to form aspecific proportion of all dimples along the outer surface of a golfball as deep dimples. For instance, it may be desirable to form alldimples, i.e. 100%, as deep dimples. In other embodiments, it may bedesirable to form at least 95% of all dimples as deep dimples. Or, itmay be desirable to form at least 90% of all dimples as deep dimples.Alternatively, it may be desirable to form at least 85% , at least 80%,at least 75%, at least 70%, at least 65%, at least 60% , at least 55%,at least 50%, at least 45%, at least 40%, at least 35%, at least 30%, atleast 25%, at least 20%, at least 15%, at least 10%, at least 5%, or atleast 1% as deep dimples.

In forming golf balls with a particular number of deep dimples, it willbe appreciated that the molding equipment employed to form such ballsutilizes a molding chamber having a molding surface with a correspondingnumber of outwardly extending protuberances or projections as describedherein.

Furthermore, the processes and equipment described herein for reactioninjecting molding a polyurethane or polyurethane derivative material,are well suited for forming a golf ball with a relatively largeproportion of deep dimples. Although not wishing to be bound to anyparticular theory or limiting reason, it is believed that the mixing andmolding characteristics of the molding material and that associated withthe process and equipment, enable and promote the formation of one ormore cover layers that define a large number of well defined deepdimples.

One particularly preferred embodiment golf ball includes multiplepopulations of dimples along its outer surface. For example, two, three,four, five, six or more different types or populations of dimples may beprovided. One or more of the multiple populations are preferably deepdimples. The other populations may include a wide array of dimple typessuch as, but not limited to, conventional dimples, non-conventionaldimples, or dimples known in the prior art.

In general, as dimples are made deeper, the ball will fly lower ascompared to the use of dimples that are shallower. As the number of deepdimples increases, the ball will exhibit a lower flight trajectory.Accordingly, the preferred approach is to utilize a smaller number ofdeep dimples. However, for other applications, the present inventionincludes a ball with many deep dimples.

The overall shape of the dimples, including deep dimples, may be nearlyany shape. For example, shapes such as hexagon, pentagon, triangle,ellipse, circle, etc. are all suitable. There is no limit to the numberof shapes, although some shapes are preferred over others. At present,circular dimples are preferred. As for the cross-sectionalconfiguration, the dimples may utilize any geometry. For instance,dimples may be defined by a constant curve or a multiple curvature ordual radius configuration or an elliptical or teardrop shaped region.

FIG. 19 illustrates a preferred embodiment molding apparatus 1000 inaccordance with the present invention. Molding apparatus 1000 comprisestwo mold halves 1020 and 1040 that each define a hemispherical portionof a molding chamber 1024 and 1044. Defined along the outer surface ofthe hemispherical portion of the molding chamber 1024 are a plurality ofraised protrusions or support pins 1032. These raised regions or supportpins form dimples in a cover layer in a golf ball formed using moldingapparatus 1000. Also provided along the outer surface of thehemispherical molding chamber 1024 are a plurality of outwardlyextending or raised regions or support pins 1026, 1028, and 1030. Theseraised regions are of a height greater than the height of the raisedregions 1032. Specifically, the raised regions 1026, 1028, and 1030 formdeep dimples as described herein. These raised regions are used toretain and support a golf ball core placed in the mold. These raisedregions also serve to form deep dimples 1018 in the golf ball 1010. Apassage 1022 is provided in the mold half 1020 as will be appreciated.The passage 1022 provides communication and a path for a flowablemoldable material to be introduced into the molding chamber. The moldingapparatus 1000 also includes a second molding portion or plate 1040. Theplate 1040 defines a hemispherical molding chamber 1044 also having aplurality of raised regions or support pins along its outer surface.Specifically, raised regions 1046 and 1048 are provided similar to thepreviously described raised regions 1026, 1028, and 1030. The moldingplate 1040 also defines a channel 1042 extending from the moldingchamber 1044 to the exterior of the plate. Most preferably, the moldingchannel 1042 is aligned with channel 1022 in the other plate 1020 whenthe mold is closed to provide a unitary passage providing communicationbetween the molding chamber and the exterior of the mold. It will beappreciated that this figure is not necessarily to scale, and so channel1042 would likely be significantly smaller in a commercial manufacturingapplication. Preferably, a turbulence-inducing after-mixer is providedin the mold halves as previously described in conjunction with FIGS.2-9. Similarly, provisions for a dump well and associated venting arealso provided as previously described. A golf ball core placed in themolding chamber 1024,1044 is supported by the various raised regions1026, 1028, 1030, 1046, and 1048 as previously described. Upon molding asuitable cover layer on the core or intermediate ball assembly, the golfball 1010 is produced.

Certain preferred embodiment molding equipment in accordance with thepresent invention utilize molds with molding surfaces that provide acollection of different types or heights of raised regions or outwardlyextending projections. Specifically, it may in some instances bedesirable to provide a molding surface with a first population of raisedregions that define a first type of dimple and another population ofraised regions that define deep dimples as described herein. The secondor other population of raised regions that form deep dimples mayconstitute a minority proportion or a majority proportion of all thedimples defined on the resulting golf ball. It is also contemplated toprovide a number of different shapes, sizes, heights, and configurationsor raised regions along a molding surface. As will be appreciated, thisis an efficient manner to form a golf ball with a relatively largenumber of deep dimples.

Additionally, golf balls of the present invention that comprisepolyurethane/polyurea (or other suitable materials) in any of the innerand outer cover layer may be produced by RIM, as previously described.

Golf balls and, more specifically, cover layers formed by RIM arepreferably formed by the process described in application Ser. No.09/040,798, filed Mar. 18, 1998, incorporated herein by reference, or bya similar RIM process.

The golf balls, and particularly the cover layer(s), of the presentinvention may also be formed by liquid injection molding (LIM)techniques, or any other method known in the art.

The golf balls formed according to the present invention can be coatedusing a conventional two-component spray coating or can be coated duringthe RIM process, for example, using an in-mold coating process.

Referring next to FIG. 20, a process flow diagram for forming a RIMcover of polyurethane is shown. Isocyanate from bulk storage is fedthrough line 1180 to an isocyanate (or polyisocyanate) tank 1200. Theisocyanate is heated to the desired temperature, e.g., 80° F. to about220° F., by circulating it through heat exchanger 1182 via lines 1184and 1186. Polyol, polyamine, or another compound with an active hydrogenatom is conveyed from bulk storage to a polyol tank 1208 via line 1188.The polyol is heated to the desired temperature, e.g., 90° F. to about180° F., by circulating it through heat exchanger 1190 via lines 1192and 1194. Generally, it is preferred to heat each reactive componentsuch as the isocyanate and the polyol, to a temperature such that theyhave the same viscosity. Preferably, these temperatures are about 80° F.to about 220° F. for the polyol component and about 80° F. to about 220°F. for the isocyanate component. More preferably, the polyol is at atemperature of about 100° F. and the isocyanate is at about 200° F. Drynitrogen gas is fed from nitrogen tank 1196 to isocyanate tank 1200 vialine 1197 and to polyol tank 1208 via line 1198. This gaseous blanket isused to prevent oxidation or other deleterious reaction of the injectioncomponents. Isocyanate is fed from isocyanate tank 1200 via line 1202through a metering cylinder or metering pump 1204 into recirculation mixhead inlet line 1206. An isocyanate recirculation line 1250 ispreferably utilized. Polyol is fed from polyol tank 1208 via line 1210through a metering cylinder or metering pump 1212 into a recirculationmix head inlet line 1214. A polyol recirculation line 1260 is preferablyutilized. A recirculation mix head 1216 receives isocyanate and polyol,mixes them, and provides for them to be fed through nozzle 1218 intoinjection mold 1220. The injection mold 1220 has a top mold 1222 and abottom mold 1224. Heat exchange fluid flows through cooling lines 1226in the top mold 1222 and lines 1240 in the bottom mold 1224. Thematerials are kept under controlled temperature conditions so that thedesired reaction profile is maintained. Preferably, controlledtemperatures are maintained by using oil heaters or other heating mediumalong the entirety of each of the paths or lines for the reactants.Preferably, temperature control of the isocyanate lines 1202 and 1250 isachieved by use of a heat exchanger 1300 and heat exchange line 1302 asshown in FIG. 22. Similarly, temperature control of the polyol lines1210 and 1260 is achieved by use of a heat exchanger 1310 and heatexchange line 1312 as shown in FIG. 23. Most preferably, a multiple pipeassembly is used for heat exchange in which the isocyanate or polyolmaterials flows within a central tube or conduit and a heat exchangefluid flows in another portion of the assembly, preferably disposedradially around the conduit housing the isocyanate or polyol material.An effective amount of thermal insulation is preferably disposed aroundthe exterior or outer periphery of the multiple pipe assembly.

The polyol component typically contains additives, such as stabilizers,flow modifiers, catalysts, combustion modifiers, blowing agents,fillers, pigments, optical brighteners, and release agents to modifyphysical characteristics of the cover Inside the mix head 1216, injectornozzles impinge the isocyanate and polyol at ultra-high velocity toprovide excellent mixing. Additional mixing preferably is conductedusing an after-mixer 1230, which typically is constructed inside themold between the mix head and the mold cavity.

As is shown in FIG. 21, the mold 1220 includes a golf ball cavitychamber 1232 in which a spherical golf ball mold 1234 with a dimpled,spherical mold cavity 1236 defined. Preferably, an effective amount of amold release agent is applied to the molding surfaces of the moldingchamber. The aftermixer 1230 can be a peanut aftermixer, as in shown inFIG. 5, or in some cases another suitable type, such as a heart, harp ordipper. An overflow channel 1238 or “dump well” receives overflowmaterial from the golf ball mold 1234 through a shallow vent 1242.Heating/cooling passages 1226 and 1240, which preferably are in aparallel flow arrangement, carry heat transfer fluids such as water,oil, etc. through the top mold 1222 and the bottom mold 1224. Injectionmay be performed at various pressures, but it is preferred that thepressure at which each of the components is introduced to the moldingassembly is approximately equal. Preferably, impingement pressures for aRIM process using an isocyanate and a polyol component are about 150 toabout 195 bar, and preferably about 180 bar (all pressures are gauge,i.e. above atmospheric, unless noted otherwise). For the RIM processesdescribed herein, mold cycle times may range from about 30 seconds to upto 5 minutes or more depending upon the properties of the reactants. Fora RIM system using a polyol and an isocyanate as described herein, a 60second molding cycle time has been achieved, and is preferred.

After molding, the golf balls produced may undergo various furtherprocessing steps such as buffing, trimming, milling, tumbling, paintingand marking as disclosed in U.S. Pat. No. 4,911,451, herein incorporatedby reference.

In performing a RIM operation in which polyurethane covers or other golfball components are formed, it is preferred to use a PSM 90 unitavailable from Isotherm, AG. The PSM 90 unit is used for processing ofelastomers and foamed polyurethane and polyureas. Generally, the polyoland isocyanate components are metered into the PSM 90 and at leastpartially mixed under high pressure. Depending upon the mixing headused, a wide array of different molding strategies can be used.Additionally, a design guide for after-mixers is provided by BayerCorporation under the designation “Engineering Polymers, RIM Part andMold Design, Polyurethanes, a Design Guide,” No. PU-CA007, pp. 52-53 and58, 1995, herein incorporated by reference.

The resulting golf ball is produced more efficiently and lessexpensively than balls of the prior art. Additionally, the golf balls ofthe present invention may have multiple cover layers, some of them verythin (less than 0.03 inches, more preferably less than 0.02 inches, evenmore preferably less than 0.01 inches) if desired, to produce golf ballshaving specific performance characteristics. For example, golf ballshaving softer outer cover layer(s) and harder inner cover layer(s) maybe produced. Alternatively, golf balls having harder outer coverlayer(s) and softer inner cover layer(s) may be produced. Moreover, golfballs having inner and out cover layers with similar hardnesses are alsoanticipated by the present invention.

For golf balls have three or more layers, the hardness of the layers maybe varied alternately, such as hard-soft-hard, or soft-hard-soft, andthe like, or golf balls with a cover having a hardness gradient may beproduced. The hardness gradient may start with hard inner layers closeto the core and get softer at the outer layer, or vice versa. Thisallows a lot of flexibility and control of finished golf ballproperties. As previously described, the layers may be of the same ordifferent materials, and of the same or different thicknesses.

Specifically, the golf ball of the present invention is not particularlylimited with respect to its structure and construction. By using wellknown ball materials and conventional manufacturing processes, the ballsmay be manufactured as solid golf balls including one-piece golf balls,two-piece golf balls, and multi-piece golf balls with three or morelayers and wound golf balls. Furthermore, although a RIM process hasbeen described for forming the various gold balls, cores, intermediateball assemblies, cover layers, and components thereof, it will beappreciated that other techniques may be used, such as, but not limitedto, injection molding, compression molding, cast molding, and otherprocesses known in the art.

The foregoing description is, at present, considered to be the preferredembodiments of the present invention. However, it is contemplated thatvarious changes and modifications apparent to those skilled in the art,may be made without departing from the present invention. Therefore, theforegoing description is intended to cover all such changes andmodifications encompassed within the spirit and scope of the presentinvention, including all equivalent aspects.

1. A golf ball having a plurality of deep dimples defined along an outersurface of said golf ball, said golf ball comprising: a core; and acover layer disposed about said core, said cover layer having an outersurface and a thickness and defining a plurality of dimples along saidouter surface, wherein at least 5% of said dimples have a depth greaterthan said thickness of said cover layer and extend through said coverlayer.
 2. The golf ball of claim 1, wherein at least 10% of said dimpleshave a depth greater than said thickness of said cover layer.
 3. Thegolf ball of claim 1, wherein at least 20% of said dimples have a depthgreater than said thickness of said cover layer.
 4. The golf ball ofclaim 1, wherein at least 30% of said dimples have a depth greater thansaid thickness of said cover layer.
 5. The golf ban of claim 1, whereinat least 40% of said dimples have a depth greater than said thickness ofsaid cover layer.
 6. The golf ball of claim 1, wherein at least 50% ofsaid dimples have a depth greater than said thickness of said coverlayer.
 7. The golf ball of claim 1, wherein at least 60% of said dimpleshave a depth greater than said thickness of said cover layer.
 8. Thegolf ball of claim 1, wherein at least 70% of said dimples have a depthgreater than said thickness of said cover layer.
 9. The golf ball ofclaim 1, wherein at least 80% of said dimples have a depth greater thansaid thickness of said cover layer.
 10. The golf ball of claim 1,wherein at least 90% of said dimples have a depth greater than saidthickness of said cover layer.
 11. The golf ball of claim 1, wherein allof said dimples have a depth greater than said thickness of said coverlayer.
 12. A golf ball comprising: a core; and a cover layer disposedabout said core, said cover layer having a thickness and defining atleast two populations of dimples along an outer surface of said coverlayer, wherein a first population of dimples includes dimples having adepth greater than said thickness of said cover layer and a secondpopulation of dimples includes dimples having a depth less than saidthickness of said cover layer, said first population constituting atleast a minority proportion of the total number of dimples defined alongsaid outer surface of said cover layer.
 13. The golf ball of claim 12,wherein said first population constitutes about half of the total numberof dimples defined along said outer surface of said cover layer.
 14. Thegolf ball of claim 12, wherein said first population constitutes amajority of the total number of dimples defined along said outer surfaceof said cover layer.
 15. The golf ball of claim 12, wherein said coverlayer defines three populations of dimples.
 16. The golf ball of claim12, wherein said cover layer defines four populations of dimples. 17.The golf ball of claim 12, wherein said cover layer defines fivepopulations of dimples.
 18. The golf ball of claim 12, wherein saidcover layer defines six populations of dimples.
 19. The golf ball ofclaim 12, wherein said cover layer is formed via reaction injectionmolding.